DOS2 player here too.
For starters combat has a complete different feel to it, since it follows DnD rules and all, though many elements like high ground advantage still re-appear. There are also surfaces but they're nowhere near as prevalent as they were in DOS2 (don't expect fights scenes to become sea of flames on the first turn). Dice rolls are also a much more present mechanic, its not uncommon to have attacks that only have a 55% chance of hitting, so you must take that into account also.
Combat also feels kinda brutal at times, in DOS2 you'd be murdering everything in sight, but here taking a more conservative approach is advisable, especially since rest isn't as basic as it was in DOS2 (though its still a lot more forgiving than in other crpgs).
Story feels more serious in general. There's still some of that laid back and chaotic feeling from DOS2, but the game does a much better job at making you feel empathetic towards the characters (i guess close-up cinematics help in that aspect). I'd say story and its presentation have a much more "The Witcher 3" feel to it than DOS2, even camera angles and animations remind me of it. Plenty of story checks also rely on dice rolls, things like having origin characters die at the very beginning due to really bad roll can 100% happen.
